Generally, in MRIs, only a one-dimensional direction is specified and an arbitrary plane with a predetermined thickness is selectively excited using a radio wave (hereinafter, referred to as an RF) and a gradient magnetic field. In addition, there is a spectral-spatial (hereinafter, referred to as SS) method of specifying two directions instead of the entire plane and exciting selectively only the inside of a region limited by the two directions (for example, refer to NPL 1). In the SS method, in order to realize such excitation, an RF for calculating a waveform from the excitation profile (hereinafter, referred to as a 2DRF) is applied together with an oscillating gradient magnetic field.
Since a signal can be acquired by exciting only the inside of a region selected by restriction in the two-dimensional direction in the SS method, a signal from the outside of the region can be effectively suppressed. For example, this SS method is used for the navigator echo sequence (hereinafter, referred to as navi-echo) for tracking the movement of the diaphragm (for example, refer to NPL 2). In the navi-echo, the vicinity of the diaphragm is excited in a cylindrical shape in a body axial direction using the SS method, and a temporal change of the diaphragm position in an axial direction of a region excited in the cylindrical shape is detected from signals generated from the region to monitor the respiratory motion.